Recently, a great deal of research has been made for conducting polymers. These polymers have both metallic and polymeric properties and thus have electric conductivity. Due to this advantageous characteristic of conducting polymers, their utilities are very wide and have an indefinite potential for application in various industrial fields.
In electronic/electric component fields, conducting polymers have been applied to an electrolytic capacitor, an electric dual layer condenser, a switching device, a non-linear device, a field effect transistor, a photo-recording material, a display device, an anisotropic conducting sensor and other components, and research is continuously performed for further application of those conducting polymers.
In order for a polymer to show electric conductivity, it should undergo a doping process. Various doping processes can be used for doping on a polymer. In particular, protonic acid doping phenomena were first observed from polyacetylene, and thereafter it has been found that if an organic compound containing different species of elements, such as polyaniline, polypyrrole and etc., was treated with a protonic acid, their electric and magnetic properties would be significantly changed.
Among various conducting polymers, protonic acid doping for polyaniline, which is stable in the air and can be easily produced, has been widely researched. The conductivity of polyaniline synthesized chemically or electrochemically may be also changed by its pH. It may show a very wide range of conductivity values with respect to the pH, such as about 5 S/cm for pH=-1.about.+1, while about 10.sup.-10 S/cm for pH=5.about.6.
Since such a conducting polymer is hardly dissolved in a solvent after protonic acid doping, many problems are raised in treating or applying it.
Recently, it has been found that conducting polymer films can be formed from an organic acid doped polyaniline solution, and they show the conductivity of about 100 to 400 S/cm.
However, because those films may be formed from various organic acids, they are very brittle and the effect of aging on their electric conductivity is very severe. Indeed, since organic acids and solvents used in forming those films do not have an environmental affinity, many problems occur in treating or in using them.
According to a conventional method of a conducting polymer, a polymer is prepared in non-conducting powder or film form and then chemically treated in a certain manner to show conductivity.
Conducting polymers produced in this way will exhibit different conductivities in terms of chemical agents used in producing them, in concentrations thereof, and in treating processes employed. However, once they have an electrically conducting property, their workability rapidly deteriorates, thereby making it impossible to use them in a desired purpose or shape.